A novel copper-catalyzed formal diastereoselective [4 + 3] cycloaddition of 2-arylaziridines and 2-substituted cyclopentadiene was developed. This transformation provided an efficient protocol for the assembly of a highly strained bridged azabicyclo[3.2.1]octane scaffold, which is widespread in bioactive natural products. A likely mechanism showed that the reaction proceeds through [3 + 2] cycloaddition, ring opening, and aza-Michael addition cascade reaction. This protocol features high efficiency and diastereoselectivity, wide functional group compatibility, and a cheap catalyst.